I bought the tmobile version of iphone + on preorder and want to try then out. If I'm not satisfied, I know I can take my phone after 40 days to AT&T as long as I pay the phone off beforehand (I'm financing it) tmobile will unlock it. I know it's the exact same phone hardware wise and lte band wise but will my MMS and Visual voicemail work too not being the native AT&T phone? Thanks